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The Caspian Sea is one of the largest salt water bodies of the Earth, located at the junction of Europe and Asia. Its total area is about 370 thousand square meters. km. The reservoir receives more than 100 water flows. The largest rivers flowing into - Volga, Ural, Emba, Terek, Sulak, Samur, Kura, Atrek, Sefidrud.

The Volga River - the pearl of Russia

The Volga is a river that flows through the territory of the Russian Federation and partially crosses Kazakhstan. Belongs to the largest and long rivers on the ground. The total length of the Volga is more than 3500 km. The river originates in the village of Volgoverkhovye, Tver Region, located on Russian Federation.

It flows into the Caspian Sea, but does not have a direct outlet to the World Ocean, so it is classified as an internal drain. The watercourse receives about 200 tributaries and has more than 150 thousand drains. Today, reservoirs have been built on the river, allowing to regulate the flow, due to which the fluctuations in the water level have been sharply reduced.

The fishery of the river is diverse. Melon growing prevails in the Volga region: the fields are occupied by grain and industrial crops; salt is mined. Oil and gas fields have been discovered in the Ural region. The Volga is the largest river flowing into the Caspian Sea, so it has great importance For Russia. The main transport facility that allows crossing this stream is the longest one in Russia.

Ural - a river in Eastern Europe

The Ural, like the Volga River, flows on the territory of two states - Kazakhstan and the Russian Federation. historical name- Yaik. It originates in Bashkortostan at the top of the Uraltau ridge. The Ural River flows into the Caspian Sea. Its basin is the sixth largest in the Russian Federation, and the area is more than 230 square meters. km. Interesting fact: the Ural River, contrary to popular belief, belongs to the inland European river, and only its upper course in Russia belongs to Asia.

The mouth of the stream gradually becomes shallower. At this point, the river splits into several branches. This feature is typical throughout the entire length of the channel. During floods, you can watch the Ural overflow its banks, in principle, like many other Russian rivers flowing into the Caspian Sea. This is especially observed in places with a gently sloping coastline. Flooding occurs at a distance of up to 7 meters from the riverbed.

Emba - the river of Kazakhstan

Emba is a river flowing on the territory of the Republic of Kazakhstan. The name comes from the Turkmen language, literally translated as "the valley of food." The river basin with an area of ​​40 thousand square meters. km. The river begins its journey in the mountains of Mugodzhary and, flowing along, is lost among the swamps. Asking which rivers flow into the Caspian Sea, we can say that in full-flowing years, the Emba reaches its basin.

Natural resources such as oil and gas are being exploited along the coastline of the river. The issue of passing the border between Europe and Asia along the Emba watercourse, as in the case of the river. Ural open topic and today. The reason for this is natural factor: mountains Ural Range, which are the main reference point for drawing boundaries, disappear, forming a homogeneous area.

Terek - mountain water stream

Terek is a river of the North Caucasus. The name literally translates from Turkic as "poplar". The Terek flows out of the glacier of Mount Zilga-Khokh, located in the Trusovsky Gorge of the Caucasus Range. passes through the lands of many states: North Ossetia, Georgia, Stavropol Territory, Kabardino-Balkaria, Dagestan and Chechen Republic. It flows into the Caspian Sea and the Arkhangelsk Bay. The length of the river is just over 600 km, the basin area is about 43 thousand square meters. km. An interesting fact is that every 60-70 years the flow forms a new transit arm, while the old one loses its strength and disappears.

The Terek, like other rivers flowing into the Caspian Sea, is widely used to satisfy human economic needs: it is used to irrigate the arid territories of the adjacent lowlands. There are also several hydroelectric power plants on the water stream, the total average annual output of which is more than 200 million kWh. In the near future, it is planned to launch additional additional stations.

Sulak - water stream of Dagestan

Sulak is a river that connects the streams of the Avar Koisu and the Andi Koisu. It flows through the territory of Dagestan. It starts in the Main Sulak Canyon and ends its journey in the waters of the Caspian Sea. The main purpose of the river is the water supply of two cities of Dagestan - Makhachkala and Kaspiysk. Also, several hydroelectric power stations are already located on the river, it is planned to launch new ones to increase the generated capacity.

Samur - the pearl of South Dagestan

Samur is the second largest river in Dagestan. Literally, the name from the Indo-Aryan is translated as "an abundance of water." It originates at the foot of Mount Guton; It flows into the waters of the Caspian Sea in two branches - Samur and Small Samur. The total length of the river is just over 200 km.

All rivers flowing into the Caspian Sea are of great importance for the territories through which they flow. Samur is no exception. The main direction of using the river is irrigation of lands and providing residents of nearby cities with drinking water. It was because of this that a hydroelectric complex and a number of the Samur-Divichinsky canal were built.

At the beginning of the 20th century (2010), Russia and Azerbaijan signed an interstate agreement requiring both sides to rationally use the resources of the Samur River. The same agreement introduced territorial changes between these countries. The border between the two states has been moved to the middle of the hydroelectric complex.

Kura - the largest river of Transcaucasia

Asking the question which rivers flow into the Caspian Sea, I want to describe the flow of the Kuru. It flows on the land of three states at once: Turkey, Georgia, Azerbaijan. The length of the stream is more than 1000 km, the total area of ​​the basin is about 200 thousand square meters. km. Part of the basin is located on the territory of Armenia and Iran. The source of the river is located in the Turkish province of Kars, flows into the waters of the Caspian Sea. The path of the river is thorny, laid among hollows and gorges, for which it got its name, which in Megrelian means “nibble”, that is, the Kura is a river that “gnaws” itself even among the mountains.

There are many cities on it, such as Borjomi, Tbilisi, Mtskheta and others. It plays an important role in meeting the economic needs of the inhabitants of these cities: fishing is carried out, hydroelectric power stations are located, and the Mingachevir reservoir created on the river is one of the main fresh water reserves for Azerbaijan. Unfortunately, the ecological state of the stream leaves much to be desired: the level of harmful substances exceeds the permissible limits by several times.

Features of the Atrek River

Atrek is a river located on the territory of Iran and Turkmenistan. It originates in the Turkmen-Kharasan mountains. Due to the active use in economic needs for irrigation of land, the river became shallow. For this reason, it reaches the Caspian Sea only during the flood period.

Sefidrud - the abundant river of the Caspian

Sefidrud is a major river of the Iranian state. It was originally formed by the confluence of two water streams - Kyzyluzen and Shakhrud. Now it flows out of the Shabanau reservoir and flows into the depths of the Caspian Sea. The total length of the river is over 700 km. The creation of a reservoir has become a necessity. It made it possible to minimize the risks of flooding, thereby securing the cities located in the river delta. Water is used to irrigate land with total area more than 200 thousand hectares of land.

As can be seen from the presented material, the Earth's water resources are in an unsatisfactory state. The rivers flowing into the Caspian Sea are actively used by man to meet his needs. And this has a detrimental effect on their condition: watercourses are depleted and polluted. That is why scientists around the world are sounding the alarm and conducting active propaganda, calling for saving and conserving water on Earth.

The Caspian Sea is the largest enclosed body of water on the planet Earth, located on the continent of Eurasia - in border area states Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. In fact, it is a giant lake left after the disappearance of the ancient Tethys ocean. Nevertheless, there is every reason to consider it as an independent sea (this is indicated by salinity, a large area and decent depth, the bottom of the oceanic crust and other signs). In terms of maximum depth, it is the third among closed reservoirs - after lakes Baikal and Tanganyika. In the northern part of the Caspian Sea (a few kilometers from north coast- parallel to it) is the geographical border between Europe and Asia.

Toponymy

• Other names: throughout the history of mankind, different peoples of the Caspian Sea had about 70 different names. The most famous of them are: Khvalynskoe or Khvalisskoe (it took place in the times of Ancient Rus', arose by the name of the people praise, who lived in the Northern Caspian and traded with the Russians), Girkan or Dzhurdzhan (derived from the alternative names of the city of Gorgan, located in Iran), Khazar, Abeskun (after the name of the island and city in the Kura delta - now flooded), Saray, Derbent, Sikhay .
• Origin of name: according to one of the hypotheses, its modern and most ancient name, The Caspian Sea received from a tribe of nomadic horse breeders the Caspians who lived in 1st millennium BC on the southwest coast.

Morphometry

• Catchment area: 3,626,000 km².
• Mirror area: 371,000 km².
• Coastline length: 7,000 km.
• Volume: 78,200 km³.
• Average depth: 208 m
• Max Depth: 1025 m.

Hydrology

• The presence of a constant flow: no, it's pointless.
• Tributaries:, Ural, Emba, Atrek, Gorgan, Heraz, Sefidrud, Astarchay, Kura, Pirsagat, Kusarchay, Samur, Rubas, Darvagchay, Ulluchay, Shuraozen, Sulak, Terek, Kuma.
• Bottom: very varied. On not great depths sandy soil with an admixture of shells is common, in deep water places it is silty. Pebble and rocky places can be found in the coastal strip (especially where mountain ranges adjoin the sea). In the estuarine areas, the underwater soil consists of river sediments. The Kara-Bogaz-Gol bay is notable for the fact that its bottom is a powerful layer of mineral salts.

Chemical composition

• Water: brackish.
• Salinity: 13 g / l.
• Transparency: 15 m.

Geography

Rice. 1. Map of the Caspian Sea basin.

• Coordinates: 41°59′02″ s. sh., 51°03′52″ E d.
• Height above sea level:-28 m.
• Coastal landscape: thanks to coastline The Caspian Sea is very long, and it is located in different geographical zones - the coastal landscape is diverse. In the northern part of the reservoir, the shores are low, swampy, in places of the deltas of large rivers they are indented by numerous channels. The eastern shores are mostly limestone - desert or semi-desert. The western and southern shores adjoin mountain ranges. The greatest indentation of the coastline is observed in the west - in the area Absheron Peninsula, as well as in the east - in the area of ​​​​the bays of Kazakh and Kara-Bogaz-Gol.
• Settlements on the coast:
  • Russia: Astrakhan, Derbent, Kaspiysk, Makhachkala, Olya.
  • Kazakhstan: Aktau, Atyrau, Kuryk, Sogandyk, Bautino.
  • Turkmenistan: Ekerem, Karabogaz, Turkmenbashi, Khazar.
  • Iran: Astara, Balboser, Bender-Torkemen, Bender-Anzeli, Neka, Chalus.
  • Azerbaijan: Alyat, Astara, Baku, Dubendi, Lankaran, Sangachali, Sumgayit.

interactive map

Ecology

The ecological situation in the Caspian Sea is far from ideal. Almost all large rivers flowing into it are polluted by the effluents of industrial enterprises located upstream. This could not but affect the presence of pollutants in the waters and bottom sediments of the Caspian - over the past half century, their concentration has increased markedly, and the content of some heavy metals has already exceeded the permissible limits.

In addition, the waters of the Caspian Sea are constantly polluted by domestic wastewater from coastal cities, as well as during oil production on the continental shelf, and during its transportation.

Fishing in the Caspian Sea

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• Artificial settlement: not all of the above fish species in the Caspian Sea are native. About 4 dozen species came by chance (for example, through channels from the basins of the Black and Baltic Seas), or were deliberately populated by humans. An example is the mullet. Three Black Sea species of these fish - striped mullet, sharp-nosed mullet and golden mullet - were released in the first half of the 20th century. The striped mullet did not take root, but the blackfin with golden mullet have successfully acclimatized, and by the current moment they have settled in virtually the entire water area of ​​the Caspian Sea, having formed several commercial herds. At the same time, fish feed faster than in the Black Sea, and reach larger sizes. In the second half of the last century (starting from 1962), attempts were also made to populate such Far Eastern salmon fish as pink salmon and chum salmon in the Caspian Sea. In total, several billion fry of these fish were released into the sea within 5 years. Pink salmon did not survive in the new range, but on the contrary, chum salmon successfully took root and even began to spawn in the rivers flowing into the sea. However, she could not reproduce in sufficient quantities and gradually disappeared. There are as yet no favorable conditions for its full-fledged natural reproduction (there are very few places where spawning and development of fry could successfully occur). To ensure them, river reclamation is needed, otherwise, without human help (artificial sampling of eggs and its incubation), fish will not be able to maintain their numbers.

Fishing places

In fact, fishing is possible at any point on the coast of the Caspian Sea, which can be reached by land or water. Which species of fish will be caught at the same time depends on local conditions, but to a greater extent on whether rivers flow here. As a rule, in places where estuaries and deltas (especially large watercourses) are located, the water in the sea is strongly desalinated, therefore, freshwater fish (carp, catfish, bream, etc.) usually predominate in catches; rivers (barbels, shemaya). From marine species in desalinated areas, those for which salinity does not matter are caught (mullet, some of the gobies). In certain periods of the year, semi-anadromous and migratory species can be found here, feeding in the sea, and entering the rivers for spawning (sturgeon, some of herring, Caspian salmon). In places where there are no flowing rivers, freshwater species are found in a slightly smaller number, but at the same time, marine fish appear, usually avoiding desalinated areas (for example - sea ​​zander). Away from the coast, fish are caught that prefer salt water, and deep sea species.

In total, there are 9 places of interest in terms of fishing:

1. North Shore (RF)- this area is located on the northern coast of the Russian Federation (from the Volga delta to the Kizlyar Bay). Its main features are the insignificant salinity of the water (the lowest in the Caspian Sea), shallow depth, the presence of multiple shoals, islands, and highly developed aquatic vegetation. In addition to the Volga delta with its numerous channels, bays and erics, it also includes the estuarine seaside, called the Caspian peals. These places are popular with Russian fishermen, and for good reason: the conditions for fish are very favorable here, and there is also a good forage base. The ichthyofauna in these parts may not shine with a richness of species, but it is distinguished by its abundance, and some of its representatives reach a very considerable size. Usually the basis of catches are freshwater fish, typical for the Volga basin. Most often caught: perch, pike perch, roach (more precisely, its varieties, called roach and ram), rudd, asp, sabrefish, bream, goldfish, carp, catfish, pike. Bursh, silver bream, white-eye, blue bream are somewhat less common. There are also representatives of sturgeon (sturgeon, stellate sturgeon, beluga, etc.), salmon (nelma, brown trout - Caspian salmon) in these places, but their catch is prohibited.
2. Northwestern coast (RF)- this section covers the western coast of the Russian Federation (from Kizlyar Bay to Makhachkala). The Kuma, Terek and Sulak rivers flow here - they carry their waters both along natural channels and artificial channels. In this area there are bays, among which are quite large ones (Kizlyarsky, Agrakhansky). The sea in these places is shallow. Of the fish in the catches, freshwater species predominate: pike, perch, carp, catfish, rudd, bream, barbel, etc., marine species are also caught here, for example, herring (black-backed, shad).
3. West Bank (RF)- from Makhachkala to the border of the Russian Federation with Azerbaijan. An area where mountain ranges adjoin the sea. The salinity of the water here is somewhat higher than in previous places, therefore, marine species are more common in the catches of fishermen (sea pike, mullet, herring). However, freshwater fish are by no means uncommon.
4. West Bank (Azerbaijan)- from the border of the Russian Federation with Azerbaijan to the Absheron Peninsula. Continuation of the section where mountain ranges adjoin the sea. Fishing here is even more similar to typical sea fishing, thanks to fish such as hart and golden mullet (mullet) and several types of gobies, which are also caught here. In addition to them, there are kutum, herring, and some typically freshwater species, for example, carp.
5. Southwest coast (Azerbaijan)- from the Absheron Peninsula to the border of Azerbaijan with Iran. Most of this area is occupied by the delta of the Kura River. Here the same species of fish are caught that were listed in the previous paragraph, but freshwater ones are somewhat more common.
6. North Shore (Kazakhstan)- this area covers north coast Kazakhstan. Here are the Ural delta and state reserve"Akzhaiyk", therefore fishing directly in the river delta and in some water area adjacent to it is prohibited. Fishing is possible only outside the reserve - upstream from the delta, or in the sea - at some distance from it. Fishing near the Ural delta has much in common with fishing at the confluence of the Volga - almost the same species of fish are found here.
7. Northeast coast (Kazakhstan)- from the mouth of the Emba to Cape Tyub-Karagan. In contrast to the northern part of the sea, where the water is greatly diluted by large rivers flowing into it, its salinity is slightly increased here, therefore, those fish species appear that avoid desalinated areas, for example, sea zander, which is caught in the Dead Kultuk Bay. Also, other representatives of marine fauna are often found in the catches.
8. Eastern coast (Kazakhstan, Turkmenistan)- from Cape Tyub-Karagan to the border of Turkmenistan and Iran. Differs in the almost complete absence of flowing rivers. The salinity of the water here is at its highest. Of the fish in these places, marine species predominate, the main catches are mullet, pike perch and gobies.
9. South Shore (Iran)- covers South coast Caspian. Throughout the entire length of this section adjoins the sea mountain range Elburz. Many rivers flow here, most of which are small streams, there are also several medium and one large river. Of the fish, in addition to marine species, there are also some freshwater, as well as semi-anadromous and anadromous species, for example, sturgeons.

Features of fishing

The most popular and catchy amateur tackle that is used on the Caspian coast is a heavy spinning rod converted into a “sea bottom”. Usually it is equipped with a strong spool, on which a fairly thick line (0.3 mm or more) is wound. The thickness of the fishing line is determined not so much by the size of the fish as by the mass of a rather heavy sinker, which is necessary for an ultra-long cast (in the Caspian it is widely believed that the farther from the shore the casting point is, the better). After the sinker comes a thinner fishing line - with several leashes. As a bait, shrimps and amphipods that live in coastal thickets of algae are used - if it is supposed to catch sea fish, or an ordinary bait like a worm, cockchafer larvae and others - if freshwater species are found in the fishing area.

The length of the coastline of the Caspian Sea is estimated at about 6500-6700 kilometers, with islands - up to 7000 kilometers. The shores of the Caspian Sea in most of its territory are low-lying and smooth. In the northern part, the coastline is indented by water channels and islands of the Volga and Ural deltas, the shores are low and swampy, and the water surface is covered with thickets in many places. The east coast is dominated by limestone shores adjacent to semi-deserts and deserts. The most winding coasts are on the west coast in the area of ​​the Apsheron Peninsula and on the east coast in the area of ​​the Kazakh Gulf and Kara-Bogaz-Gol. The territory adjacent to the Caspian Sea is called the Caspian Sea.

The Caspian Sea is notable for the fact that its western coast belongs to Europe, and the eastern one is located on the territory of Asia. This is a huge body of salt water. It is called the sea, but, in fact, it is a lake, as it has no connection with the oceans. Therefore, it can be considered the largest lake in the world.

Square water giant is 371 thousand square meters. km. As far as depth is concerned, Northern part the sea is rather shallow, and the southern one is deep. The average depth is 208 meters, but it does not give any idea of ​​​​the thickness of the water mass. The entire reservoir is divided into three parts. These are the Northern, Middle and Southern Caspian. The northern one is the sea shelf. It accounts for only 1% of the total volume of water. This part ends behind the Kizlyar Bay near the island of Chechen. The average depth in these places is 5-6 meters.

In the Middle Caspian, the seabed noticeably decreases, and the average depth reaches 190 meters. The maximum is equal to 788 meters. This part of the sea contains 33% of the total volume of water. And the South Caspian is considered to be the deepest one. It absorbs 66% of the total water mass. The maximum depth was noted in the South Caspian depression. She is equal 1025 meters and is considered the official maximum sea depth to date. The Middle and South Caspian are approximately equal in area and occupy a total of 75% of the area of ​​the entire reservoir.

The maximum length is 1030 km and the corresponding width is 435 km. The minimum width is 195 km. The average figure corresponds to 317 km. That is, the reservoir has an impressive size and is rightfully called the sea. The length of the coastline, together with the islands, reaches almost 7 thousand km. As for the water level, it is 28 meters below the level of the World Ocean.

The most interesting thing is that the level of the Caspian Sea is subject to cyclicity. The water goes up and down. Water levels have been measured since 1837. According to experts, over the past thousand years, the level has fluctuated within 15 meters. This is a very big number. And they associate it with geological and anthropogenic (human impact on environment) processes. However, it has been noted that since the beginning of the 21st century, the level of the huge reservoir has been steadily rising.

The Caspian Sea is surrounded by 5 countries. These are Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan. Moreover, Kazakhstan has the longest coastline. Russia is in 2nd place. But the length of the coastline of Azerbaijan reaches only 800 km, but in this place there is the largest port in the Caspian Sea. This is, of course, Baku. The city is home to 2 million people, and the population of the entire Absheron Peninsula is 2.5 million people.

"Oil Rocks" - a city in the sea
These are 200 platforms with a total length of 350 kilometers

Notable is the settlement of oil workers, which is called " Oil Stones". It is located 42 km east of Absheron in the sea and is a creation of human hands. All residential and industrial buildings are built on metal overpasses. People serve drilling rigs pumping oil from the bowels of the earth. Naturally, there are no permanent residents in this village.

In addition to Baku, along the banks of the salt reservoir, there are other big cities. At the southern tip is the Iranian city of Anzali with a population of 111 thousand people. This is the largest Iranian port in the Caspian. Kazakhstan owns the city of Aktau with a population of 178 thousand people. And in the northern part, directly on the Ural River, is the city of Atyrau. It is inhabited by 183 thousand people.

The Russian city of Astrakhan also has the status of a seaside city, although it is 60 km away from the coast and is located in the delta of the Volga River. This regional center with a population of more than 500 thousand people. Directly on the seashore are such Russian cities as Makhachkala, Kaspiysk, Derbent. The latter refers to ancient cities peace. People have been living in this place for more than 5 thousand years.

Many rivers flow into the Caspian Sea. There are about 130 of them. The largest of them are the Volga, Terek, Ural, Kura, Atrek, Emba, Sulak. It is the rivers, and not the precipitation, that feed the huge body of water. They give him up to 95% of water per year. The basin of the reservoir is 3.626 million square meters. km. These are all rivers with their tributaries flowing into the Caspian. The territory is huge, it includes bay Kara-Bogaz-Gol.

This bay is more correctly called a lagoon. It means a shallow body of water, separated from the sea by a sandy spit or reefs. There is such a spit in the Caspian. And the strait through which water flows from the sea is 200 km wide. True, people with their restless and ill-conceived activities almost destroyed Kara-Bogaz-Gol. They blocked off the lagoon with a dam, and its level dropped sharply. But after 12 years, the mistake was corrected and the strait was restored.

The Caspian has always been developed shipping. In the Middle Ages, merchants brought exotic spices and skins of snow leopards from Persia to Rus' by sea. Today, the reservoir connects the cities located on its banks. practiced ferry crossings. There is a water connection with the Black and Baltic Seas through rivers and canals.

Caspian Sea on the map

The reservoir is also important from the point of view fisheries, because sturgeon lives in it in large numbers and gives caviar. But today the number of sturgeons has significantly decreased. Ecologists propose to ban the capture of this valuable fish until the population recovers. But this issue has not yet been resolved. The number of tuna, bream, pike perch also decreased. Here it is necessary to take into account the fact that poaching is highly developed at sea. The reason for this is the difficult economic situation in the region.

And, of course, a few words must be said about oil. The extraction of "black gold" at sea began in 1873. The areas adjacent to Baku have become a real gold mine. There were more than 2 thousand wells here, and oil production and processing was carried out on an industrial scale. At the beginning of the 20th century it was the center of the international oil industry. In 1920, Azerbaijan was occupied by the Bolsheviks. Oil wells and factories were requisitioned. The entire oil industry came under the control of the USSR. In 1941, Azerbaijan supplied 72% of all oil produced in the socialist state.

In 1994, the "Contract of the Century" was signed. He started international development Baku oil fields. The main Baku-Tbilisi-Ceyhan pipeline allows Azerbaijani oil to flow directly to the Mediterranean port of Ceyhan. It was put into operation in 2006. To date, oil reserves are estimated at 12 trillion. US dollars.

Thus, it is clear that the Caspian Sea is one of the most important economic regions of the world. The political situation in the Caspian region is rather complicated. For a long time there have been debates about maritime borders between Azerbaijan, Turkmenistan and Iran. There were many inconsistencies and disagreements, which negatively affected the development of the region.

This ended on August 12, 2018. On this day, the states of the "Caspian Five" signed the Convention on the Legal Status of the Caspian Sea. This document demarcated the bottom and subsoil, and each of the five countries (Russia, Kazakhstan, Iran, Turkmenistan, Azerbaijan) received its share in the Caspian basin. The rules for the implementation of navigation, fishing, scientific research, and the laying of pipelines were also approved. The boundaries of territorial waters received the status of state.

Yuri Syromyatnikov

The Caspian Sea is inland and is located in a vast continental depression on the border of Europe and Asia. The Caspian Sea has no connection with the ocean, which formally allows it to be called a lake, but it has all the features of the sea, since it had connections with the ocean in past geological epochs.

The area of ​​the sea is 386.4 thousand km2, the volume of water is 78 thousand m3.

The Caspian Sea has a vast drainage basin, with an area of ​​about 3.5 million km2. The nature of landscapes, climatic conditions and types of rivers are different. Despite its vastness, only 62.6% of its area is in waste areas; about 26.1% - for drainless. The area of ​​the Caspian Sea itself is 11.3%. 130 rivers flow into it, but almost all of them are located in the north and west (and the eastern coast does not have a single river reaching the sea at all). largest river the Caspian basin - the Volga, which provides 78% of the river water entering the sea (it should be noted that more than 25% of the Russian economy is located in the basin of this river, and this undoubtedly determines many other features of the waters of the Caspian Sea), as well as the Kura and Zhaiyk rivers (Ural), Terek, Sulak, Samur.

In physical and geographical terms and according to the nature of the underwater relief, the sea is divided into three parts: northern, middle and southern. The conditional boundary between the northern and middle parts runs along the line of Chechen Island–Cape Tyub-Karagan, between the middle and southern parts - along the line of Zhiloy Island–Cape Kuuli.

The shelf of the Caspian Sea, on average, is limited by depths of about 100 m. The continental slope, which begins below the edge of the shelf, ends in the middle part at about 500–600 m, in the southern part, where it is very steep, at 700–750 m.

The northern part of the sea is shallow, its average depth is 5–6 m, the maximum depths of 15–20 m are located on the border with the middle part of the sea. The bottom relief is complicated by the presence of banks, islands, furrows.

The middle part of the sea is a separate basin, an area maximum depths which - the Derbent depression - is shifted to the western coast. The average depth of this part of the sea is 190 m, the greatest is 788 m.

The southern part of the sea is separated from the middle part by the Apsheron threshold, which is a continuation Greater Caucasus. Depths above this underwater ridge do not exceed 180 m. The deepest part of the South Caspian basin with a maximum sea depth of 1025 m is located east of the Kura delta. Several underwater ridges up to 500 m high rise above the bottom of the basin.

The shores of the Caspian Sea are diverse. In the northern part of the sea, they are quite strongly indented. Here are the bays of Kizlyar, Agrakhan, Mangyshlak and many shallow bays. Notable peninsulas: Agrakhansky, Buzachi, Tyub-Karagan, Mangyshlak. Large islands in the northern part of the sea are Tyuleniy, Kulaly. In the deltas of the Volga and Ural rivers, the coastline is complicated by many islets and channels, which often change their position. Many small islands and banks are located on other parts of the coastline.

The middle part of the sea has a relatively flat coastline. On the western coast, on the border with the southern part of the sea, the Apsheron Peninsula is located. To the east of it, the islands and banks of the Apsheron archipelago stand out, of which the most large island Residential. The eastern shore of the Middle Caspian is more indented, the Kazakh Bay stands out here with the Kenderli Bay and several capes. The largest bay of this coast is Kara-Bogaz-Gol.

South of the Absheron Peninsula are the islands of the Baku archipelago. The origin of these islands, as well as some of the jars east coast the southern part of the sea is associated with the activity of underwater mud volcanoes lying at the bottom of the sea. On the eastern shore are the large bays of Turkmenbashi and Turkmensky, and near it is the island of Ogurchinsky.

One of the most striking phenomena of the Caspian Sea is the periodic variability of its level. In historical times, the Caspian Sea had a lower level than the World Ocean. Fluctuations in the level of the Caspian Sea are so great that for more than a century they have attracted the attention of not only scientists. Its peculiarity is that in the memory of mankind its level has always been below the level of the World Ocean. Since the beginning of instrumental observations (since 1830) of the sea level, the amplitude of its fluctuations has been almost 4 m, from -25.3 m in the eighties of the XIX century. to -29 m in 1977. In the last century, the level of the Caspian Sea has changed significantly twice. In 1929 it stood at a mark of about -26 m, and since it had been close to this mark for almost a century, this position of the level was considered as a long-term or secular average. In 1930, the level began to decline rapidly. Already by 1941, it had dropped by almost 2 m. This led to the drying up of vast coastal areas of the bottom. The decrease in the level, with its small fluctuations (short-term insignificant rises in the level in 1946-1948 and 1956-1958), continued until 1977 and reached the mark of -29.02 m, i.e., the level took the lowest position for last 200 years.

In 1978, contrary to all forecasts, the sea level began to rise. As of 1994, the level of the Caspian Sea was at -26.5 m, that is, in 16 years the level has risen by more than 2 m. The rate of this rise is 15 cm per year. The level increment in some years was higher, and in 1991 it reached 39 cm.

The general fluctuations in the level of the Caspian Sea are superimposed by its seasonal changes, the average long-term of which reaches 40 cm, as well as surge phenomena. The latter are especially pronounced in the Northern Caspian. The northwestern coast is characterized by large surges created by the prevailing, especially in the cold season, storms of eastern and southeastern directions. Over the past decades, a number of large (more than 1.5–3 m) surges have been observed here. A particularly large surge with catastrophic consequences was noted in 1952. Fluctuations in the level of the Caspian Sea cause great damage to the states surrounding its water area.

Climate. The Caspian Sea is located in the temperate and subtropical climatic zones. Climatic conditions change in the meridional direction, since the sea stretches for almost 1200 km from north to south.

In the Caspian region, various circulation systems interact, however, easterly winds prevail throughout the year (the influence of the Asian high). The position at rather low latitudes provides a positive balance of heat inflow, so the Caspian Sea serves as a source of heat and moisture for passing air masses for most of the year. The average annual temperature in the northern part of the sea is 8–10°С, in the middle part - 11–14°С, in the southern part – 15–17°С. However, in the northernmost parts of the sea, the average January temperature is from –7 to –10°C, and the minimum temperature during arctic air intrusions is up to –30°C, which determines the formation of the ice cover. In summer, rather high temperatures dominate over the entire region under consideration - 24–26°C. Thus, the Northern Caspian is subject to the most sharp temperature fluctuations.

The Caspian Sea is characterized by a very small amount of precipitation per year - only 180 mm, and most of it falls on the cold season of the year (from October to March). However, the Northern Caspian differs in this respect from the rest of the basin: here the average annual precipitation is less (only 137 mm for the western part), and the distribution over the seasons is more even (10–18 mm per month). In general, we can talk about proximity climatic conditions to the arid ones.

Water temperature. The distinctive features of the Caspian Sea (great differences in depths in different parts of the sea, the nature of the bottom relief, isolation) have a certain influence on the formation of temperature conditions. In the shallow North Caspian, the entire water column can be considered as homogeneous (the same applies to shallow bays located in other parts of the sea). In the Middle and South Caspian, surface and deep masses separated by a transitional layer can be distinguished. In the Northern Caspian and in the surface layers of the Middle and Southern Caspian, the water temperature varies over a wide range. In winter, temperatures vary from north to south from less than 2 to 10°С, the water temperature near the western coast is 1–2°С higher than near the eastern one, in the open sea the temperature is higher than near the coasts: by 2–3°С in the middle part and by 3–4°С in the southern part of the sea. In winter, the temperature distribution is more uniform with depth, which is facilitated by the winter vertical circulation. In moderate and harsh winters in the northern part of the sea and shallow bays on the east coast, the water temperature drops to freezing.

In summer, the temperature varies in space from 20 to 28°C. The highest temperatures are observed in the southern part of the sea; temperatures are also quite high in the well-warmed shallow North Caspian. The zone of distribution of the lowest temperatures is adjacent to the east coast. This is due to the rise of cold deep waters to the surface. Temperatures are also relatively low in the poorly heated deep-water central part. In the open areas of the sea, in late May–early June, the formation of a temperature jump layer begins, which is most clearly expressed in August. Most often it is located between 20 and 30 m in the middle part of the sea and 30 and 40 m in the south. In the middle part of the sea, due to the surge near the eastern coast, the shock layer rises close to the surface. In the bottom layers of the sea, the temperature during the year is about 4.5°C in the middle part and 5.8–5.9°C in the south.

Salinity. Salinity values ​​are determined by such factors as river runoff, water dynamics, including mainly wind and gradient currents, the resulting water exchange between the western and eastern parts of the Northern Caspian and between the Northern and Middle Caspian, the bottom topography, which determines the location of waters with different salinity, mainly along the isobaths, evaporation, which ensures the shortage of fresh water and the inflow of more saline ones. These factors collectively affect the seasonal differences in salinity.

The Northern Caspian can be considered as a reservoir of constant mixing of river and Caspian waters. The most active mixing occurs in the western part, where both river and Central Caspian waters directly enter. In this case, horizontal salinity gradients can reach 1‰ per 1 km.

The eastern part of the Northern Caspian is characterized by a more uniform salinity field, since most of river and sea (Middle Caspian) waters enter this area of ​​the sea in a transformed form.

According to the values ​​of horizontal salinity gradients, in the western part of the Northern Caspian, a river-sea contact zone can be distinguished with water salinity from 2 to 10‰, in the eastern part from 2 to 6‰.

Significant vertical salinity gradients in the Northern Caspian are formed as a result of the interaction of river and sea waters, with runoff playing a decisive role. The intensification of vertical stratification is also facilitated by the unequal thermal state of the water layers, since the temperature of the surface desalinated waters coming from the coast in summer is 10–15°C higher than that of the bottom ones.

In the deep basins of the Middle and South Caspian, salinity fluctuations in the upper layer are 1–1.5‰. The largest difference between the maximum and minimum salinity was noted in the area of ​​the Apsheron threshold, where it is 1.6‰ in surface layer and 2.1‰ at the horizon of 5 m.

The decrease in salinity along West Bank The southern Caspian in the 0–20 m layer is caused by the runoff of the Kura River. The influence of the Kura runoff decreases with depth; at the horizons of 40–70 m, the range of salinity fluctuations is no more than 1.1‰. Along the entire western coast to the Absheron Peninsula stretches a strip of desalinated water with a salinity of 10–12.5‰ coming from the Northern Caspian.

In addition, salinity increases in the South Caspian due to the removal of saline waters from bays and inlets on the eastern shelf under the action of southeasterly winds. In the future, these waters are transferred to the Middle Caspian.

In the deep layers of the Middle and South Caspian, salinity is about 13‰. In the central part of the Middle Caspian, such salinity is observed at horizons below 100 m, and in the deep part of the South Caspian, the upper boundary of waters with increased salinity drops to 250 m. Obviously, vertical mixing of waters is difficult in these parts of the sea.

Surface water circulation. Currents in the sea are mainly wind-driven. In the western part of the Northern Caspian, currents of the western and eastern quarters are most often observed, in the eastern - southwestern and southern. The currents caused by the runoff of the Volga and Ural rivers can be traced only within the estuarine coast. The prevailing current velocities are 10–15 cm/s, in the open areas of the Northern Caspian maximum speeds about 30 cm/s.

IN coastal areas in the middle and southern parts of the sea, in accordance with the wind directions, currents of the northwestern, northern, southeastern and southern directions are observed; currents often occur off the eastern coast east direction. Along the western coast of the middle part of the sea, the most stable currents are southeast and south. Current velocities are on average about 20–40 cm/s, the maximum ones reach 50–80 cm/s. Other types of currents also play a significant role in the circulation of sea waters: gradient, seiche, inertial ones.

ice formation. The Northern Caspian is covered with ice annually in November, the area of ​​the freezing part of the water area depends on the severity of the winter: in severe winters, the entire Northern Caspian is covered with ice, in soft ice it stays within the 2–3 meter isobath. The appearance of ice in the middle and southern parts of the sea falls on December-January. Near the eastern coast, ice is of local origin, near the western coast - most often brought from the northern part of the sea. In severe winters, shallow bays freeze off the eastern coast of the middle part of the sea, coastlines and fast ice form off the coast, and drifting ice spreads to the Absheron Peninsula in abnormally cold winters off the western coast. The disappearance of the ice cover is observed in the second half of February–March.

Oxygen content. The spatial distribution of dissolved oxygen in the Caspian Sea has a number of regularities.
The central part of the Northern Caspian is characterized by a fairly uniform distribution of oxygen. An increased oxygen content is found in the areas of the pre-estuary seashore of the Volga River, a lower one - in the southwestern part of the Northern Caspian.

In the Middle and South Caspian, the highest oxygen concentrations are confined to coastal shallow areas and pre-estuary seashores of rivers, with the exception of the most polluted areas of the sea (Baku Bay, Sumgait region, etc.).

In the deep-water regions of the Caspian Sea, the main pattern is preserved in all seasons - a decrease in oxygen concentration with depth.
Due to the autumn-winter cooling, the density of the waters of the North Caspian increases to a value at which it becomes possible for the flow of North Caspian waters with a high oxygen content along the continental slope to significant depths of the Caspian Sea.

The seasonal distribution of oxygen is mainly related to the annual course and seasonal ratio of production-destruction processes occurring in the sea.

In spring, the production of oxygen in the process of photosynthesis quite significantly covers the decrease in oxygen due to a decrease in its solubility with an increase in water temperature in spring.

In the areas of the estuarine coasts of the rivers feeding the Caspian Sea, in spring there is a sharp increase in the relative oxygen content, which in turn is an integral indicator of the intensification of the photosynthesis process and characterizes the degree of productivity of the mixing zones of sea and river waters.

In summer, due to significant warming of water masses and activation of photosynthesis processes, the leading factors in the formation of the oxygen regime in surface waters are photosynthetic processes, in near-bottom waters - biochemical oxygen consumption by bottom sediments.

Due to the high temperature of the waters, the stratification of the water column, the large influx of organic matter and its intense oxidation, oxygen is quickly consumed with its minimal entry into the lower layers of the sea, as a result of which an oxygen deficiency zone is formed in the Northern Caspian. Intensive photosynthesis in open waters deep-sea regions of the Middle and South Caspian covers the upper 25-meter layer, where oxygen saturation is more than 120%.

In autumn, in the well-aerated shallow water areas of the Northern, Middle and Southern Caspian, the formation of oxygen fields is determined by the processes of water cooling and the less active, but still ongoing process of photosynthesis. The oxygen content is rising.

The spatial distribution of nutrients in the Caspian Sea reveals the following patterns:

• increased concentrations of biogenic substances characterize the areas of pre-estuary seashores of rivers that feed the sea and shallow areas of the sea subject to active anthropogenic influence (Baku Bay, Turkmenbashi Bay, water areas adjacent to Makhachkala, Fort Shevchenko, etc.);
• The Northern Caspian, which is a vast mixing zone of river and sea waters, is characterized by significant spatial gradients in the distribution of nutrients;
• in the Middle Caspian, the cyclonic nature of the circulation contributes to the upwelling of deep waters with a high content of nutrients into the overlying layers of the sea;
• in the deep water areas of the Middle and South Caspian, the vertical distribution of nutrients depends on the intensity of the convective mixing process, and their content increases with depth.

The dynamics of nutrient concentrations during the year in the Caspian Sea is influenced by such factors as seasonal fluctuations in the biogenic runoff into the sea, the seasonal ratio of production-destruction processes, the intensity of exchange between soil and water mass, ice conditions in winter time in the Northern Caspian, the processes of winter vertical circulation in the deep sea areas.

In winter, a significant area of ​​the Northern Caspian is covered with ice, but biochemical processes are actively developing in the under-ice water and ice. The ice of the Northern Caspian, being a kind of accumulator of biogenic substances, transforms these substances entering the sea from and from the atmosphere.

As a result of the winter vertical circulation of waters in the deep-sea regions of the Middle and Southern Caspian in the cold season, the active layer of the sea is enriched with nutrients due to their supply from the underlying layers.

Spring for the waters of the North Caspian is characterized by a minimum content of phosphates, nitrites and silicon, which is explained by the spring outbreak of phytoplankton development (silicon is actively consumed by diatoms). High concentrations of ammonium and nitrate nitrogen, characteristic of the waters of a large area of ​​the Northern Caspian during floods, are due to intensive flushing by river waters.

In the spring season, in the area of ​​water exchange between the Northern and Middle Caspian in the subsurface layer, with the maximum oxygen content, the content of phosphates is minimal, which, in turn, indicates the activation of the photosynthesis process in this layer.

In the South Caspian, the distribution of nutrients in spring is basically similar to their distribution in the Middle Caspian.

IN summer time in the waters of the Northern Caspian, a redistribution of various forms of biogenic compounds is found. Here, the content of ammonium nitrogen and nitrates significantly decreases, while at the same time there is a slight increase in the concentrations of phosphates and nitrites and a rather significant increase in the concentration of silicon. In the Middle and South Caspian, the concentration of phosphates has decreased due to their consumption in the process of photosynthesis and the difficulty of water exchange with the deep water accumulation zone.

In autumn, in the Caspian Sea, due to the cessation of the activity of some types of phytoplankton, the content of phosphates and nitrates increases, and the concentration of silicon decreases, as an autumn outbreak of diatoms occurs.

Oil has been produced on the shelf of the Caspian Sea for more than 150 years.

Currently, large reserves of hydrocarbons are being developed on the Russian shelf, the resources of which on the Dagestan shelf are estimated at 425 million tons of oil equivalent (of which 132 million tons of oil and 78 billion m3 of gas), on the shelf of the Northern Caspian - 1 billion tons of oil .

In total, about 2 billion tons of oil have already been produced in the Caspian.

Losses of oil and products of its processing during extraction, transportation and use reach 2% of the total volume.

The main sources of pollutants, including oil products, entering the Caspian Sea are carry-over with river runoff, discharge of untreated industrial and agricultural effluents, domestic wastewater from cities and towns located on the coast, shipping, exploration and exploitation of oil and gas fields located at the bottom of the sea, transportation of oil by sea. 90% of pollutants with river runoff are concentrated in the Northern Caspian, industrial effluents are confined mainly to the area of ​​the Apsheron Peninsula, and increased oil pollution of the Southern Caspian is associated with oil production and oil exploration drilling, as well as active volcanic activity (mud) in zone of oil and gas bearing structures.

From the territory of Russia, about 55 thousand tons of oil products enter the Northern Caspian every year, including 35 thousand tons (65%) from the Volga River and 130 tons (2.5%) from the Terek and Sulak rivers.

The thickening of the film on the water surface up to 0.01 mm disrupts the processes of gas exchange and threatens the death of hydrobiota. Toxic for fish is the concentration of oil products 0.01 mg/l, for phytoplankton - 0.1 mg/l.

The development of oil and gas resources of the bottom of the Caspian Sea, the estimated reserves of which are estimated at 12–15 billion tons of standard fuel, will become the main factor in the anthropogenic load on the ecosystem of the sea in the coming decades.

Caspian autochthonous fauna. The total number of autochthons is 513 species or 43.8% of the entire fauna, which include herring, gobies, mollusks, etc.

arctic views. The total number of the Arctic group is 14 species and subspecies, or only 1.2% of the entire fauna of the Caspian (mysids, sea cockroach, white salmon, Caspian salmon, Caspian seal, etc.). The basis of the Arctic fauna is crustaceans (71.4%), which easily tolerate desalination and live at great depths of the Middle and South Caspian (from 200 to 700 m), since the lowest water temperatures (4.9– 5.9°C).

mediterranean views. These are 2 types of mollusks, needle-fish, etc. At the beginning of the 20s of our century, the mollusk mitilyastra penetrated here, later 2 types of shrimp (with mullets, during their acclimatization), 2 types of mullet and flounder. Some Mediterranean species entered the Caspian after the opening of the Volga-Don Canal. Mediterranean species play a significant role in the fish food base of the Caspian Sea.

Freshwater fauna (228 species). This group includes anadromous and semi-anadromous fish (sturgeon, salmon, pike, catfish, cyprinids, as well as rotifers).

sea ​​views. These are ciliates (386 forms), 2 species of foraminifera. There are especially many endemics among higher crustaceans (31 species), gastropod molluscs (74 species and subspecies), bivalve mollusks (28 species and subspecies) and fish (63 species and subspecies). The abundance of endemics in the Caspian Sea makes it one of the most unique brackish water bodies on the planet.

The Caspian Sea provides more than 80% of the world's sturgeon catch, most of which falls on the North Caspian.

To increase the catches of sturgeon, which dropped sharply during the years of sea level drop, a set of measures is being implemented. Among them - a complete ban on sturgeon fishing in the sea and its regulation in rivers, an increase in the scale of factory breeding of sturgeons.